In the typical whirlpool or hot tub, the water is normally pulled out of the hot tub or whirlpool through a drain system at the base of the tub into the inlet of a suction pump and then drained or recirculated back to the tub or pool through jets located around the interior wall of the pool or tub. The jet action or pulsing effect provides a relaxing environment to the individuals sitting in the relatively hot water. It is well known that whirlpools containing turbulent hot circulating water has a therapeutic effect on the occupants.
In conventional hot tubs and whirlpools currently in use, drains are subject to constant suction by the pumps to provide the recirculating effect and the turbulence in the pool to bring about the desired therapeutic effect. Since it is possible that an individual sitting in the pool may be in the immediate proximity of a drain, there are concerns that one may not be readily able to remove oneself therefrom. There are two reasons for this. One is the possibility that the forces holding the individual on the drain due to the pump suction are often of a sufficient strength to prevent one from lifting themselves from the drain and exiting from the pool or tub. Even the smallest pump is capable of developing very high suction levels. The second possibility is the whirlpool or undertow effect that produces fluid flow patterns that capture and retain a bather. This concern is particularly great when large horsepower pumps are used that create high flow rates in the neighborhood of the pool drains. Unfortunately, there is often no ready way to turn off the pump to eliminate the suction or high flow effect which could hold one on or in the neighborhood of the drain and cause injury or possibly result in someone drowning. The industry has suggested methods for eliminating the development of high suction levels through the use of multiple interconnected drains. These low-tech solutions recognize that disembowelment occurs very rapidly when bathers sit on non-interconnected drains and effectively stop all flow. The industry has also proposed pressure detection devices that shut off the pump at preset critical suction levels. These high-tech solutions raise questions of reliability, calibration, stability, and maintenance capability by foreseeable pool operators. To deal with the whirlpool or undertow problem, the industry has suggested limitations on the drain flow rate. Unfortunately, high capacity large horsepower systems for the larger pools cannot usually adopt low flow rates at the drains without compromising, for example, the aggressive nature of recirculating jets used for therapeutic treatment in hot tubs. This high drain flow rate problem which gives rise to the whirlpool or undertow effect has not been addressed by the industry.